1. Field of the Invention
The present invention relates to a backlight module of a thin film transistor liquid crystal display, and more particularly, to a backlight control device for controlling a driving current of an LED.
2. Description of the Prior Art
Ordinarily, the current control integrated circuit of a light-emitting diode (LED) uses fixed resistance to control the driving current of the backlight module to control the brightness of the backlight module. The disadvantage is that once the resistance value of the bias resistor is established, the driving current of backlight module cannot be adjusted, and a long-term use of circuit components can cause an unexpected variation in the driving current of backlight module. Further, the driving current in certain types of LED, such as Organic LED (OLED), may be changed due to a change in the operating temperature of the current regulator. As a result, the brightness of the LED in the backlight module may be adversely affected. Therefore, a method and an apparatus capable of controlling the driving current for backlight modules in LCD systems are needed.
FIG. 1 illustrates a prior art programmable control method to regulate the brightness of LEDs in a backlight module 100. Microcontrollers are an example where users can input the desired current value or voltage value to an LED controller 103 through a user interface 101 of the microcontroller 102. According to the current value or voltage value stored in registers, the desired current value or voltage value is generated and provided to the current output unit, and the output current 104 generated by the current output unit is used to regulate the brightness of an LED 105.
However, the method described above uses programming interfaces to regulate the brightness of LEDs, so that the backlight can not regulate the brightness in displaying video. Therefore, the related art can not dynamically reduce the brightness of backlight when the lower brightness is desired. Further, the related art can not dynamically enhance the brightness of backlight when the higher brightness is desired. The related art uses brightness predetermined and inputted by a user, and the backlight module can not dynamically regulate the brightness later on. As a result, it causes low quality in the brightness contrast of images.